Assemblies for blowing liquids from a vehicle exterior are well known and typically include a plenum for distributing air to a plurality of nozzles, which in turn emit air toward a vehicle. The plenum is supplied air by a blower system having an inlet for drawing air in. The plenum then supplies pressurized air to the nozzles. The blower system typically includes an impeller that is rotated in a housing by an electric motor. The impeller can act as a pump or compressor to pressurize air as it enters the plenum and then force it to and out the nozzles.
These high volume air blowers are known to be quite noisy during operation and also consume considerable electric power when running at full capacity. As is also known, there are significant periods during operation of a vehicle wash where there is no demand for a dryer system to blow liquid from a vehicle, i.e., when no vehicles are passing through the vehicle wash system or are being treated by other wash components. As it is generally detrimental to an electric motor to frequently start and stop, approaches for reducing the airflow output from the device without shutting off the motor have been attempted.
Among these approaches have included pivoted damper plates disposed at the blower inlet (or the outlet) to vary flow through the device. Such an approach yields a bulky and complicated device particularly since the inclusion of a rotatable gate must still accommodate a safety mesh typically installed over the inlet to prevent objects from entering the plenum or a person from reaching into the blower interior, which could result in an injury. In operation, these dampers generally rotate 90 degrees between a closed position where the faces of the dampers generally overlie the blower inlet and an open position where only the edges of the dampers face the blower inlet such that the air inlet is substantially exposed.
Another approach involves mounting a sliding gate adjacent the blower inlet, which may be moved linearly to cover/expose the inlet. However, this arrangement likewise is complex and bulky requiring space for the gate to slide to one side of the blower inlet such that it is fully exposed to allow air to enter the housing. Thus, a significant range of movement is required to slide the gate to open and close the inlet opening, which must be accomplished against large frictional resistance.
While other approaches for reducing/limiting dryer output when unnecessary have also been devised, they all suffer from a variety of disadvantages. For example, these approaches often fail to provide an efficient seal between the closure mechanism and the blower inlet, which still results in the motor operating unnecessarily at all times as air can still be drawn into the air inlet. This inefficient seal can even cause the blower motor to work harder, when the gate mechanism is disposed over which can decrease the life of the blower. Additionally, these approaches are generally bulky and thus expensive which makes them disadvantageous.